An uncut integrated circuit formed in a semiconductor wafer, an integrated circuit cut into chip-like sections, and an integrated circuit (i.e., a device under test) such as an integrated circuit cut into chip-like sections and packaged or molded are subjected to a test as to whether or not they provide performance as per specification.
A probe card used in such a test generally comprises a probe base plate having a plurality of signal paths, i.e., electrically-conductive paths, and a plurality of contacts arranged on one face of the probe base plate and electrically connected to the conductive paths.
As such a probe base plate, a wiring board made of glass epoxy resin, a ceramic base plate made of ceramic, a flexible multi-layer wiring board made of an electrically insulated resin such as polyimide resin, or a base plate for combined use with the flexible multi-layer wiring board disposed on the underside of the ceramic base plate may be used.
Recently, testing of an integrated circuit under high temperature is under way. In this case, an integrated circuit is heated to a predetermined temperature by a heating element provided in a stage where the integrated circuit is disposed, whereby a probe base plate where a contact is disposed is also heated upon receipt of the heat from the stage and the integrated circuit. As a result, the integrated circuit and the probe base plate are thermally expanded.
If, however, an amount of thermal expansion of the integrated circuit and that of the probe base plate are different, a relative physical relation between an electrode of the integrated circuit and a tip of the contact changes, resulting in some contact with their tips left unpressed against the electrode of the integrated circuit.
Thus, a test apparatus is proposed wherein a heating element disposed within a probe base plate is heated to heat the probe base plate, thereby adjusting the temperature of the probe base plate. This is shown generally in Japanese Patent Publication No. 4-359445.
However, in the test apparatus as described in Japanese Patent Publication No. 4-359445, which uses a probe card, though it is difficult to provide a heating element of large capacity in a probe base plate, only a single metal layer is provided as a heating element in the probe base plate. Thus, it takes a long time for the probe card, particularly a ceramic base plate, to be heated to a predetermined temperature, and operating efficiency is low.
For instance, in a test apparatus to move a stage relative to the probe card every time a test of wafer is finished, the probe card is exposed to ambient temperature whenever the stage is separated from the probe card, and the temperature of the probe card lowers.
In an apparatus to test multiple wafers by dividing them into lots for testing per lot, each lot including a plurality of wafers, a probe card is exposed to ambient temperature not only each time a test of one wafer is finished, but also every time a stage is moved to replace the wafers per lot. In such an apparatus, the temperature of the probe base plate lowers while the probe card is exposed to ambient temperature.
In view of the above, in a test apparatus, the temperature of a probe card should be raised again to a predetermined temperature for the subsequent wafer test. In the conventional test apparatus, however, it takes a long time to raise the lowered temperature of the probe card again to a predetermined temperature, resulting in low test efficiency.